IB Chemistry Topic 11 Measurement and data processing
11.1 Uncertainties and errors in measurement and results
 Qualitative data includes all nonnumerical information obtained from observations not from measurement.
 Quantitative data are obtained from measurements, and are always associated with random errors/uncertainties, determined by the apparatus, and by human limitations such as reaction times.
 Propagation of random errors in data processing shows the impact of the uncertainties on the final result.
 Experimental design and procedure usually lead to systematic errors in measurement, which cause a deviation in a particular direction.
 Repeat trials and measurements will reduce random errors but not systematic errors.
 Distinction between random errors and systematic errors.
 Record uncertainties in all measurements as a range (+) to an appropriate precision.
 Discussion of ways to reduce uncertainties in an experiment.
 Propagation of uncertainties in processed data, including the use of percentage uncertainties.
 Discussion of systematic errors in all experimental work, their impact on the results and how they can be reduced.
 Estimation of whether a particular source of error is likely to have a major or minor effect on the final result.
 Calculation of percentage error when the experimental result can be compared with a theoretical or accepted result.
 Distinction between accuracy and precision in evaluating results.

How to calculation uncertainty using uncertainty propagation. Multiply and divide add percentage error. Plus and minus add raw uncertainties. Also calculations for percentage error and the halfway method for when uncertainty is not mainly coming from the instrumentation.
0:33 Key terms (random/systematic error, precision, accuracy) 2:12 Example causes of systematic error 4:48 Reducing random error 5:30 Determining uncertainty 8:03 Halfway method 10:04 Significant zeros 11:43 Significant figures and calculations 13:57 Key terms (Absolute/percentage uncertainty/error) 15:02 Uncertainty propagation 17:51 Percentage error 19:21 Measuring with glassware (titrations) 
11.2 Graphical techniques
 Graphical techniques are an effective means of communicating the effect of an independent variable on a dependent variable, and can lead to determination of physical quantities.
 Sketched graphs have labelled but unscaled axes, and are used to show qualitative trends, such as variables that are proportional or inversely proportional.
 Drawn graphs have labelled and scaled axes, and are used in quantitative measurements.
 Drawing graphs of experimental results including the correct choice of axes and scale.
 Interpretation of graphs in terms of the relationships of dependent and independent variables.
 Production and interpretation of bestfit lines or curves through data points, including an assessment of when it can and cannot be considered as a linear function.
 Calculation of quantities from graphs by measuring slope (gradient) and intercept, including appropriate units.

How to do graphs to the IB Chemistry requirements
0:26 Describing graphs 0:50 Determining gradient 1:14 The Perfect graph  line of best fit 1:48 The Perfect graph  error bars 2:21 The Perfect graph  labelling and units 2:28 The Perfect graph  uncertainties and significant figures 2:41 The Perfect graph  grid lines and data points 2:43 The Perfect graph  relevant annotations 3:03 The Perfect graph  Example 2 
EXPERIMENTAL VIDEOS:




EXAM PAST PAPER QUESTION VIDEOS:





How to Measure Quiz:
End of Unit Quiz Topic 11:
11.3 Spectroscopic identification of organic compounds SL
 The degree of unsaturation or index of hydrogen deficiency (IHD) can be used to determine from a molecular formula the number of rings or multiple bonds in a molecule.
 Mass spectrometry (MS), proton nuclear magnetic resonance spectroscopy (1H NMR) and infrared spectroscopy (IR) are techniques that can be used to help identify compounds and to determine their structure.
 Determination of the IHD from a molecular formula.
 Deduction of information about the structural features of a compound from percentage composition data, MS, 1H NMR or IR.

How to read graphs from HNMR, mass, and IR spectroscopy and determine IHD.
0:26 Instrument overview and use of EMS 0:44 EMS formulas 1:14 Infrared IR spectroscopy 5:16 Proton nuclear magnetic resonance H1 NMR spectroscopy 10:11 Index of hydrogen deficiency IHD 13:29 Mass spectrometry MS 
EXAM PAST PAPER QUESTION VIDEOS SL:

21.1 Spectroscopic identification of organic compounds HL:
 Structural identification of compounds involves several different analytical techniques including IR, 1H NMR and MS.
 In a high resolution 1H NMR spectrum, single peaks present in low resolution can split into further clusters of peaks.
 The structural technique of single crystal Xray crystallography can be used to identify the bond lengths and bond angles of crystalline compounds.
 Explanation of the use of tetramethylsilane (TMS) as the reference standard.
 Deduction of the structure of a compound given information from a range of analytical characterization techniques (Xray crystallography, IR, 1H NMR and MS).

More detail on HNMR spectroscopy and calculations
0:17 HNMR spinspin coupling 0:27 Tetramethylsilane TMS standard 1:05 High resolution HNMR 4:48 Splitting rules 5:35 Integration of the graph 5:46 Example problem 7:30 Xray crystallography 
EXAM PAST PAPER QUESTION VIDEOS HL:

CHEMICAL INSTRUMENT VIDEOS:
Mass spectrometry (MS):

Infrared spectroscopy (IR):



UltravioletVisible Spectroscopy (UVVis):

Proton Nuclear Magnetic Resonance (NMR):



High Performance Liquid Chromatography (HPLC):

Gas Chromatography (GC):



Xray diffraction:

Microwave reactor (EXTENSION  not in IB syllabus):


